An operational example of a mobile terminal provided with the CMIP (Client MIP) function (or MIPv4 (Mobile Internet Protocol version 4) function), connected to a network including PMIP clients, is shown below.
That is, with a mobile terminal connected to a network including a PMIP client, the method is considered of transmitting AA (Agent Advertisement) defined in MIPv4 (RFC (Request For Comments) 3344) to a mobile terminal and confirming whether or not the mobile terminal has a CMIP function (for example, refer to non-patent document 1).
That is to say, when a CMIP terminal receives AA, it transmits a RRQ (Registration Request: position registration request) in response to the reception. However, when the RRQ is transmitted, the network side judges that the mobile terminal has a CMIP function and the mobile terminal operates in accordance with the CMIP function.
A Simple IP (Internet Protocol) terminal cannot understand AA and tries to acquire an address in accordance with a DHCP (Dynamic Host Configuration Protocol), like a conventional IP terminal connected to a network. Instead of the Simple IP terminal, the PMIP client transmits a position registration request to HA (Home Agent), with the DHCP request as a trigger.
In the above processing operation, the CMIP terminal performs a CMIP operation exclusively. However, some operators for network administration may desire to operate the CMIP terminal with the PMIP.
However, when the CMIP terminal is connected to a network having the PMIP function, the mechanism for choosing the (PMIP or CMIP) operation of a mobile terminal, in consideration of a request from a mobile terminal side or the policy of a network, does not exist currently.    Non-patent document 1: “WiMAX End-to-End Network Systems Architecture (Stage 2: Architecture Tenets, Reference Model and Reference Points) (Part 2), 7.8 CSN Anchored Mobility Management”    Non-patent document 2: “Mobility Management using Proxy Mobile IPv4”, http://www.ietf.org/internet-drafts/draft-leung-mip4-proxy-mode-01.txt    Non-patent document 3: “Proxy Mobile IPv6”, http://www.ietf.org/internet-drafts/draft-sgundave-mipv6-proxymipv6-00.txt    Non-patent document 4: “Network Based Layer 3 Connectivity and Mobility Management for IPv6”, http//www.ietf.org/internet-drafts/draft-chowdhury-netmip6-0.1.txt